In an information processing system in which a client executes processing by using application software transmitted over a network, a scheme in which the client is also provided with dedicated application software for performing data (stream) processing is known. For example, a configuration is known in which a server performs edit processing and transmits the edited data to the client each time the edit processing is performed. However, when a large amount of data is to be edited using application software, use of the configuration in which a server performs edit processing and transmits the edited data to the client each time the edit processing is performed results in a significant increase in the amount of network load. On the other hand, a scheme in which the application software is transmitted to the client so as to permit the client to execute edit processing may reduce the amount of network load.
In such a scheme, however, the application software transmitted to the client could be fraudulently executed at the client side to permit acquirement of a result of the execution of the application software. Thus, there is a need to protect the application software received over the network against fraudulent use.
One known example of a scheme for protecting application software against fraudulent use is a scheme that permits use of the application software for only a predetermined period of time after a client is authenticated by a server. In such a scheme, the application software causes the server and the client to perform handshaking through network communication so as to allow the server to recognize the execution state of the application software each time the application software is executed by the client, thereby achieving the above-described protection. Japanese Unexamined Patent Application Publication No. 2002-244827 and Japanese Unexamined Patent Application Publication No. 2002-543511 disclose protection of application software against fraudulent use.